MSGnavigation (cdm-core 6.0.0-beta1 API)

java.lang.Object
- ucar.unidata.geoloc.projection.AbstractProjection
- - ucar.unidata.geoloc.projection.sat.MSGnavigation

All Implemented Interfaces:

Projection
```
@Immutable
public class MSGnavigation
extends AbstractProjection
```
Port Eumetsat MSG_navigation.c to java. from http://www.eumetsat.int/idcplg?IdcService=GET_FILE&dDocName=zip_tools_msg_nav_c&RevisionSelectionMethod=LatestReleased

Since:

Jan 9, 2010

See Also:

"http://www.eumetsat.int/idcplg?IdcService=GET_FILE&dDocName=PDF_CGMS_03&RevisionSelectionMethod=LatestReleased", "www.itc.nl/library/papers_2005/conf/gieske_pro.pdf"

Field Summary

Fields
Modifier and Type	Field and Description
`static String`	`HEIGHT_FROM_EARTH_CENTER` ********************************************************************** Introduction: ============= The Program "MSG_navigation.c" is an example code provided to give the users guidance for a possible implementation of the equations given in the LRIT/HRIT Global Specification [1] to navigate MSG (METEOSAT 8 onwards) data, i.e.
`static String`	`SCALE_X`
`static String`	`SCALE_Y`

Fields inherited from class ucar.unidata.geoloc.projection.AbstractProjection
atts, EARTH_RADIUS, INDEX_LAT, INDEX_LON, INDEX_X, INDEX_Y, isLatLon, name, PI, PI_OVER_2, PI_OVER_4, TOLERANCE

Constructor Summary

Constructors
Constructor and Description
`MSGnavigation()`
`MSGnavigation(double lat0, double lon0, double major_axis, double minor_axis, double sat_height, double scale_x, double scale_y)` Constructor

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`Projection`	`constructCopy()` copy constructor - avoid clone !!
`boolean`	`crossSeam(ProjectionPoint pt1, ProjectionPoint pt2)` Does the line between these two points cross the projection "seam", which is a discontinuity in the function latlon <-> projection plane
`boolean`	`equals(Object o)`
`double`	`getLon0()`
`int`	`hashCode()`
`ProjectionPoint`	`latLonToProj(LatLonPoint latlon)` Convert a LatLonPoint to projection coordinates.
`ProjectionRect`	`latLonToProjBB(LatLonRect rect)` Create a ProjectionRect from the given LatLonRect.
`String`	`paramsToString()` String representation of the projection parameters.
`LatLonPoint`	`projToLatLon(ProjectionPoint ppt)` Convert projection coordinates to a LatLonPoint.
`String`	`toString()` Get a String representation of this projection.

Methods inherited from class ucar.unidata.geoloc.projection.AbstractProjection
addParameter, addParameter, addParameter, addParameter, findProjectionParameter, getClassName, getHeader, getMinOrMaxLon, getName, getProjectionAttributes, getProjectionParameters, getProjectionTypeLabel, isLatLon, projToLatLonBB

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface ucar.unidata.geoloc.Projection
latLonToProj, projToLatLon

- Field Detail
  - HEIGHT_FROM_EARTH_CENTER
```
public static final String HEIGHT_FROM_EARTH_CENTER
```
    ********************************************************************** Introduction: ============= The Program "MSG_navigation.c" is an example code provided to give the users guidance for a possible implementation of the equations given in the LRIT/HRIT Global Specification [1] to navigate MSG (METEOSAT 8 onwards) data, i.e. to link the pixel coordinates column and line to the corresponding geographical coordinates latitude and longitude.
    Users should take note, however, that it does NOT provide software for reading MSG data either in LRIT/HRIT, in native or any other format and that EUMETSAT cannot guarantee the accuracy of this software. The software is for use with MSG data only and will not work in the given implementation for Meteosat first generation data.
    Two functions/subroutines are provided: pixcoord2geocoord: for conversion of column/line into lat./long. geocoord2pixcoord: for conversion of lat./long. into column/line
    The main routine gives an example how to utilize these two functions by reading a value for column and line at the start of the program on the command line and convert these values into the corresponding geographical coordinates and back again. The results are then printed out on the screen.
    To Compile the program use for example:
    COMMAND PROMPT: gcc MSG_navigation.c -o MSG_navigation -lm
    Run the program by typing
    COMMAND PROMPT: ./MSG_navigation
    ----------------------------------------------------------------------
    NOTE: Please be aware, that the program assumes the MSG image is ordered in the operational scanning direction which means from south to north and from east to west. With that the VIS/IR channels contains of 3712 x 3712 pixels, start to count on the most southern line and the most eastern column with pixel number 1,1.
    
    NOTE on CFAC/LFAC and COFF/LOFF: The parameters CFAC/LFAC and COFF/LOFF are the scaling coefficients provided by the navigation record of the LRIT/HRIT header and used by the scaling function given in Ref [1], page 28.
    COFF/LOFF are the offsets for column and line which are basically 1856 and 1856 for the VIS/IR channels and refer to the middle of the image (centre pixel). The values regarding the High Resolution Visible Channel (HRVis) will be made available in a later issue of this software.
    CFAC/LFAC are responsible for the image "spread" in the NS and EW directions. They are calculated as follows: CFAC = LFAC = 2^16 / delta with delta = 83.84333 micro Radian (size of one VIS/IR MSG pixel)
    CFAC = LFAC = 781648343.404 rad^-1 for VIS/IR
    which should be rounded to the nearest integer as stated in Ref [1].
    CFAC = LFAC = 781648343 rad^-1 for VIS/IR
    the sign of CFAC/LFAC gives the orientation of the image. Negative sign give data scanned from south to north as in the operational scanning. Positive sign vice versa.
    The terms "line" and "row" are used interchangeable.
    PLEASE NOTE that the values of CFAC/LFAC which are given in the Header of the LRIT/HRIT Level 1.5 Data (see [2]) are actually in Degrees and should be converted in Radians for use with these routines (see example and values above).
    The other parameters are given in Ref [1].
    Further information may be found in either Ref [1], Ref [2] or Ref [3] or on the Eumetsat website http://www.eumetsat.int/ .
    REFERENCE: [1] LRIT/HRIT Global Specification (CGMS 03, Issue 2.6, 12.08.1999) for the parameters used in the program. [2] MSG Ground Segment LRIT/HRIT Mission Specific Implementation, EUMETSAT Document, (EUM/MSG/SPE/057, Issue 6, 21. June 2006). [3] MSG Level 1.5 Image Data Format Description (EUM/MSG/ICD/105, Issue v5A, 22. August 2007).
    Please email the User Service (via http://www.eumetsat.int/Home/Basic/Contact_Us/index.htm) if you have any questions regarding this software.
    ================================ From simon.elliott@eumetsat.int As explained in notes 4 and 6 to the GRIB definition (and evidenced by drawing a sketch of the Earth and satellite in the equatorial plane and looking down from above), we have the following from GRIB:
    # The distance from the Earth's centre to the satellite is Nr (in units of Earth equatorial radius and multiplied by 10^6. # The distance from the Earth's centre to the tangent point on the equator is the Earths equatorial radius # The sine of the angle subtended by the Earths centre and the tangent point on the equator as seen from the spacecraft = Re / (( Nr * Re) / 10^6) = 10^6 / Nr # The angle subtended by the Earth equator as seen by the spacecraft is, by symmetry twice the inverse sine above, 2 * arcsine (10^6 / Nr) # As the number of pixels occupied by the Earth's equatorial radius is dx, the number of radians scanned by the spacecraft per pixel, Rx, is simply [2 * arcsine (10^6 / Nr)] / dx
    To calculate CFAC, one needs to know delta, the number radians per pixel which is Rx above.
    So CFAC = 2^16 / delta = 2^16 / Rx = 2^16 / {[2 * arcsine (10^6 / Nr)] / dx }
    
    **********************************************************************
    
    See Also:
    
    Constant Field Values
  - SCALE_X
```
public static final String SCALE_X
```
    See Also:
    
    Constant Field Values
  - SCALE_Y
```
public static final String SCALE_Y
```
    See Also:
    
    Constant Field Values
- Constructor Detail
  - MSGnavigation
```
public MSGnavigation()
```
  - MSGnavigation
```
public MSGnavigation(double lat0,
                     double lon0,
                     double major_axis,
                     double minor_axis,
                     double sat_height,
                     double scale_x,
                     double scale_y)
```
    Constructor
    
    Parameters:
    
    lat0 - in degrees; geosynch satelite is over this point
    
    lon0 - in degrees; geosynch satelite is over this point
    
    major_axis - in meters
    
    minor_axis - in meters
    
    sat_height - in meters
    
    scale_x - convert between aperature size in radians and distance in km (xrad = xkm / scale_x)
    
    scale_y - scale_factor = (nr - 1) * major_axis, nr = altitude of the camera from the Earths centre, measured in units of the Earth (equatorial) radius
- Method Detail
  - toString
```
public String toString()
```
    Description copied from class: AbstractProjection
    
    Get a String representation of this projection.
    
    Overrides:
    
    toString in class AbstractProjection
    
    Returns:
    
    the name of the projection. This is what gets displayed when you add the projection object to a UI widget (e.g. label, combobox)
  - constructCopy
```
public Projection constructCopy()
```
    Description copied from class: AbstractProjection
    
    copy constructor - avoid clone !!
    
    Specified by:
    
    constructCopy in class AbstractProjection
    
    Returns:
    
    a copy of this Projection.
  - paramsToString
```
public String paramsToString()
```
    Description copied from interface: Projection
    
    String representation of the projection parameters.
    
    Specified by:
    
    paramsToString in interface Projection
    
    Specified by:
    
    paramsToString in class AbstractProjection
  - latLonToProj
```
public ProjectionPoint latLonToProj(LatLonPoint latlon)
```
    Description copied from interface: Projection
    
    Convert a LatLonPoint to projection coordinates.
  - projToLatLon
```
public LatLonPoint projToLatLon(ProjectionPoint ppt)
```
    Description copied from interface: Projection
    
    Convert projection coordinates to a LatLonPoint.
  - crossSeam
```
public boolean crossSeam(ProjectionPoint pt1,
                         ProjectionPoint pt2)
```
    Description copied from interface: Projection
    
    Does the line between these two points cross the projection "seam", which is a discontinuity in the function latlon <-> projection plane
    
    Parameters:
    
    pt1 - the line goes between these two points
    
    pt2 - the line goes between these two points
    
    Returns:
    
    false if there is no seam, or the line does not cross it.
  - equals
```
public boolean equals(Object o)
```
    Overrides:
    
    equals in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - latLonToProjBB
```
public ProjectionRect latLonToProjBB(LatLonRect rect)
```
    Create a ProjectionRect from the given LatLonRect. Handles lat/lon points that do not intersect the projection panel.
    
    Specified by:
    
    latLonToProjBB in interface Projection
    
    Overrides:
    
    latLonToProjBB in class AbstractProjection
    
    Parameters:
    
    rect - the LatLonRect
    
    Returns:
    
    ProjectionRect, or null if no part of the LatLonRect intersects the projection plane
  - getLon0
```
public double getLon0()
```

Class MSGnavigation

Field Summary

Fields inherited from class ucar.unidata.geoloc.projection.AbstractProjection

Constructor Summary

Method Summary

Methods inherited from class ucar.unidata.geoloc.projection.AbstractProjection

Methods inherited from class java.lang.Object

Methods inherited from interface ucar.unidata.geoloc.Projection

Field Detail

HEIGHT_FROM_EARTH_CENTER

SCALE_X

SCALE_Y

Constructor Detail

MSGnavigation

MSGnavigation

Method Detail

toString

constructCopy

paramsToString

latLonToProj

projToLatLon

crossSeam

equals

hashCode

latLonToProjBB

getLon0